1. Field of the Invention
This invention relates to the field of high-availability computer systems and, more particularly, to providing redundant timer services.
2. Description of the Related Art
Many computer applications utilize a clock service or other timer service for a variety of reasons. For example, an application may need to produce output on a periodic basis. Accordingly, a timer service may send a notification of a timer event to the application on a periodic interval, in response to which the application may produce the required output. Alternatively, a timer event may be used to ensure that an application does not stall indefinitely when waiting for an external response.
Computer applications may also be vital to business and industry, so that failure of these applications may prove expensive. Highly reliable systems operable to provide constant availability for applications, such as a distributed system comprising multiple components, may assume a greater importance. For example, a web site may handle financial, production, sales, marketing or media applications. Failure to provide these applications to clients for even a few minutes could mean thousands or millions of dollars in lost income.
In conventional systems a central timer service may provide timer services to a cluster of application servers. However, should the timer service fail, timer events may go undelivered, thereby compromising application functionality.